1. Field of the Invention
The invention relates to an apparatus for standardizing typewriting margins. More particularly the invention relates to an apparatus which prevents inadvertent typing outside of the portion of the leaf of paper upon which it is desired to type and within the predetermined margins where it is desired not to type.
2. Description of the Prior Art
Reference is made to the following U.S. patents: Anholf U.S. Pat. No. 1,587,133, "Space Guide", issued on June 1, 1926; Lancaster U.S. Pat. No. 1,503,837, "Typewriter Sheet", issued on Aug. 5, 1924; Daboe U.S. Pat. No. 2,878,917, "Typewriter Backing Sheet With Audible Warning Device", issued on Mar. 24, 1959; Ohashi U.S. Pat. No. 898,916, "Typewriter Backing Sheet", issued on Sept. 15, 1908; and Gare, U.S. Pat. No. 2,744,606, "Line Indicating Device For Typewriters", issued on May 8, 1956.
The Anholf patent shows and describes a backing sheet which is placed behind the leaf of paper to be typed upon. A graduation for dertermining a number of lines remaining before reaching the bottom of the leaf of paper is included. A scale showing the number of typing spaces remaining on a line is also included. Alternating dark and light stripes assist the operator in alignment of the leaf of paper on the backing sheet and in determining the number of lines and spaces remaining before the margins are reached.
In the Lancaster patent, various water marks are included in the leaf of paper to apprise the operator of the location of the various margins.
The Daboe patent shows and describes an audio warning device which is of interest because it includes a scale and graduation much like that of the Anholf patent. However, in Daboe the scale is folded over the top (lateral) edge of a leaf of paper prior to insertion in the typewriter by the operator, which assists the operator in aligning the leaf of paper on the backing sheet.
The Ohashi and Gare patents (Column 3, Line 17) show graduations visible to the operator along a longitudinal edge indicating the number of lines remaining to a certain point on the backing sheet (Ohashi) or envelope (Gare). Ohashi has slots in the backing sheet for insertion of the leaf of paper to be typed upon. The slots will grip and prevent the leaf of paper from moving laterally. Gare shows a folded sheet with the graduation which is formed into an pocket. A corner of the leaf of paper is inserted in the pocket with a longitudinal edge in contact with the fold of the sheet.
None of these prior constructions automatically prevented the operator from inadvertently typing within the predetermined margins of the leaf of paper. Also, the leaf of paper was not grasped and held by the prior constructions in a secure manner against both longitudinal and lateral movement in relation to the scales and graduations, or other indicating devices.